Ice fishing rigs are devices which mount above a hole in the ice and which typically have a reel with fishing line connected to it which actuates a signaling device, such as a spring mounted flag, to indicate to the fisherman when a fish has been hooked. Ice fishing rigs which have a spring mounted flag are often referred to as "tip-ups", and are the most common type of ice fishing rig. Many different designs have been developed for ice fishing tip-ups. A typical tip-up has a board or frame which spans the hole in the ice and supports the reel which extends down into the hole. The fisherman can leave such tip-up rigs untended for substantial periods of time, and can have several tip-ups located at holes in the ice at several different locations.
One problem often encountered when using tip-ups is that the water in the hole that is spanned by the tip-up tends to freeze up over time, possibly locking up the reel or at least interfering with its operation. The fisherman may thus have to periodically check the holes in the ice under the tip-ups and chip away any ice that has formed in the hole. One type of tip-up which addresses this problem, shown in U.S. Pat. No. 5,044,108 to Rinehart, has a body in the form of a buoyant circular disk of plastic which has a sufficient diameter to span a typical ice fishing hole. Another device, shown in U.S. Pat. No. 5,235,773 to Rinehart, has a central housing which spans the hole in the ice and rigid lids hingedly connected to the center portion of the housing which are folded together during transportation and storage, and which are folded out to cover the hole in the ice when in use.